1. Field of the Invention
This invention relates to a recording member and a process for recording, and more particularly, to a heat mode recording member and a process for heat mode recording utilizing the heat mode recording member.
2. Description of the Prior Art
There have been known heat mode recording methods which comprise irradiating a recording medium by condensing a radiation beam of modulated intensity to a spot of high power density, and selectively melting, vaporizing, removing or modifying a part of the recording medium in order to record.
Heat mode recording is real time recording which does not require post-treatments such as heat development, fixation and a treating agent, and can give images of very high resolution and high contrast. Further, the recording medium for heat mode recording is not sensitive to indoor light, and the use of a darkroom procedure is therefore not necessary. Heat mode recording is suitable for recording electric signals such as the output of computers and transmitted time serial signals and add-on is possible. Heat mode recording also has the following advantages. It can be used for recording microimages and ultramicroimages, and for computer output microfilmer, microfacsimile and phototypesetting plate, and can minify the recording apparatus, elevate the function and improve the image quality.
However, at present, heat mode recording has some drawbacks and does not have sufficient practicability. For example, the recording members do not reach a level giving satisfactory sensitivity, resolving power and strength. For example, recording members utilizing a rhodium sputtered film have high strength and durability, but have only low sensitivity and require, for example, a large laser of water-cooled type having a high output. Recording members having a dispersion coating of non-metallic powder such as carbon powder have insufficient sensitivity and low resolving power and, thereby, are not suitable for microimage recording. A recording member utilizing a bismuth vapor-deposited film shows fairly high sensitivity for a metal recording member, but is still not of practically sufficient sensitivity.
Conventional recording members used for recording by deformation of a recording layer caused by thermal action of high intensity radiation do not have sufficient sensitivity, due in large part to reflection of the radiation at the surface of the recording layer. The high intensity radiation is absorbed in the recording layer and converted to thermal energy which, in turn, causes deformation such as melting, evaporation and the like in order to form a record. Therefore, sensitivity of the recording layer depends on the degree of absorption of the high intensity radiation. However, in general, the higher the degree of absorption of radiation by a material, the larger the reflection. The recording layer usually has a smooth surface for forming patterns of high resolution, and this smooth surface results in a high degree of reflection of the radiation. Therefore, the radiation is not effectively absorbed in the recording layer and converted to thermal energy, but is reflected to a great extent. For example, about 70% or more of the irradiated radiation is reflected in the case of metallic recording layers. As the result, the sensitivity is remarkably lowered.
Lowering of sensitivity of the recording layer due to the reflection of the high intensity radiation at the surface of the recording layer is theoretically in proportion to the loss of the radiation energy due to reflection.
However, when the degree of reflection at the surface of a recording layer is, for example, 80%, the loss of the radiation energy can not be always compensated for by increasing the irradiating time up to five times, because the heat generated at the recording layer diffuses to the surroundings by heat transfer. The longer the irradiation time of high intensity radiation, the more remarkable the diffusion of the heat due to heat transfer, and consequently it is very difficult to attain the temperature at which thermal deformation is caused.